Recessed downlight SLV NUMINOS DL M white/chrome 17.55 W 4000 K, driver not included, 1003909

NUMINOS DL M is a round recessed downlight 10.5 cm across, with a white trim ring and a mirror-chrome reflector. The LED module is permanently built in, and the body is a ribbed aluminium casting with leaf springs bolted to it. The beam direction is fixed — SLV sells the tiltable version as NUMINOS MOVE.

The driver is bought separately

The fitting is protection class III and runs on a constant 500 mA, so it never sees 230 V. What connects to the mains is an LED driver, and the fitting plugs into it with a connector-terminated lead. The driver is not in the box: the fitting on its own cannot be switched on after unpacking.

SLV lists four drivers for it — 1004054 at 20 W with phase dimming, 1004069 at 29 W, 1004064 at 21–29.5 W, and the 42 W bridge driver 1006459 with an interface for a radio module and DALI. The choice of driver is what decides whether and how the fitting dims, so it is worth making alongside the fitting itself.

The ceiling cut-out and the depth behind it

Installation needs a round 9 cm cut-out. The body reaches 6.1 cm above the ceiling line while the maker states 7.5 cm of installation depth — the difference is allowance for the lead and for ventilation, so it is the 7.5 cm figure to compare with the space above a suspended ceiling.

The ring stands only 7 mm below the ceiling, so the fitting reads as an aperture in the ceiling rather than as a lamp. The leaf springs hold it in a board 7 to 25 mm thick. It weighs 240 g, so the ceiling's load-bearing capacity is not a consideration.

The light it gives

The module draws 17.55 W and delivers 1660 lm at 4000 K, a neutral white — cooler and more matter-of-fact than incandescent light, but without a blue cast. An old 60 W bulb gives about 800 lm, so one of these lights like two of them.

The beam is 55 degrees, between a narrow accent and general lighting. Ra 90 means colours are rendered faithfully, which matters over a worktop, at a mirror and in a dressing room. The glare index UGR does not exceed 19, the threshold normally accepted for screen-based workplaces. The maker states 50 000 hours before output falls below 80 per cent, and energy efficiency class E.

Build and accessories

The body is aluminium and the cover polycarbonate. For the M size SLV offers interchangeable frosted, prismatic and honeycomb diffusers, which change the character of the light without replacing the fitting.